![]() ![]() The frequency determines how fast the piezo will vibrate or change state. The two main components of the electrical input are the drive frequency and voltage amplitude. Operating a piezoelectric transducer as an actuator requires an electrical input, or driving signal, with certain appropriate characteristics. For more in-depth technical information, see our Electronics Overview support article. Michael made extensive revisions and additions to the post in July 2019 to add more technical details, explanations, and up-to-date references. The George A.Authors’ Note: Jeff originally put this post together in 2016 to help people choose the best method for driving piezos, sharing his experience as an R&D engineer working on various applications for piezoelectric actuators.EE World, “ Why Use a Nonlinear Amplifier?”.For that reason, good designers look at the system requirements and don’t automatically assume they need to go digital, for some installations. (Image source: Analog Devices)Įven though digital computation is the dominant approach used now for calculation - and with excellent reason - there are many “smaller” situations where an analog computation function is a technically viable, attractive solution to the application requirements. An example is the Analog Devices AD834 (Figure 6), a monolithic, laser-trimmed four-quadrant analog multiplier (both inputs can range positive and negative) intended for use in high-frequency applications, with a bandwidth of 500 MHz the typical total full-scale error is 0.5%.įig 6: The AD834 is a high-performance analog multiplier with guaranteed performance to 500 MHz and fully specified with respect to various classes of error. The complete part comes with the datasheet, of course, which fully characterizes the block across many parameters and conditions, and so defines performance over all relevant conditions. There are many other subtleties and “tricks” they use as well as fabrication and trim steps that they can employ. Designers of these ICs can take advantage of IC process technology considerations which combining discrete components cannot do, such as using matched resistors with nearly identical drift, or current sources with nearly identical characteristics, to achieve outstanding performance. There are issues of drift, imbalance, linearity, saturation, stability, dynamic range, offsets, and many more.įor this reason, the best course is to buy an IC which incorporates the complete functional block, often with some user-settable parameters such as gain. The reality is that the concept is sound and fully proven, but an analog computation block with acceptable performance has many subtleties in hardware execution. Q: Can I just build my own analog computation circuits using inexpensive op amps and other basic, passive components?Ī: You could in principle do so, but performance would be “marginal” at best. That’s a very costly, power-hungry, and resource-hogging approach which can instead be accomplished with a few analog components Doing so would require an RF preamplifier, superfast A/D, and a short but fast-repeating “comparison loop” in software. The latter function is especially useful and is often embedded deep within in an RF-front end IC, as it is impractical to build a peak detector for RF signals with standard hardware and microprocessor. (Image source: Analog Devices)Ī: Other arrangements provide the integration and derivative functions by using a capacitor in different placements around an op amp, and using a diode and capacitor to build a peak detector (again, along with an op amp). Fig 5: Multiple analog functions can be used to “solve” polynomial equations of unlimited degree, in theory, in principle in practice, internal errors may accumulate to an unacceptable level, but the level of acceptable error is dependent on the application specifics. ![]()
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